#include <stdio.h>
#include <string.h>
int main()
 {void copystr(char *,char *,int);     
  int m;
  char str1[20],str2[20];
  printf("input string:");
  gets(str1);
  printf("which character that begin to copy?");
  scanf("%d",&m);
  if (strlen(str1)<m)
   printf("input error!");
  else
    {copystr(str1,str2,m);
     printf("result:%s\n",str2);
   }
  return 0;
 }

void copystr(char *p1,char *p2,int m)       
 {int n;
  n=0;
  while (n<m-1)
    {n++;
     p1++;
    }
  while (*p1!='\0')
    {*p2=*p1;
     p1++;
     p2++;
    }
  *p2='\0';
 }
